The new generation of communication standards uses complex modulation techniques in order to gain more spectrum efficiency. These modulation types generate signals with high varying envelopes that generally impose stringent constraints on the linearity versus power efficiency trade-off of power amplifiers. Traditional transmitter architectures include linear power amplifiers (class A or class AB) operated in back-off, which results in poor efficiency performances.
On the other hand, the proliferation and diversity of communication standards motivates the research to design a multi-standard transceiver that can be used for different communication standards. One expensive approach consists in dedicating one transmitter for each standard and switch between them depending of the input signal type or standard.
The digital transceiver, generally consisting in implementing a great portion of a transceiver in the digital domain, is another solution. Indeed, the digital transceiver is easily configured to be compliant with different standards. One approach in the design of such a digital transmitter is the use of Delta-sigma modulation (DSM) technique. This technique is used to transform the envelope and phase modulated baseband signal in one digital bit stream representing the signal. This technique also shapes the quantization noise outside of the useful bandwidth.